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This Defense Intelligence Reference Document (DIA-08-0912-005) is dated 28 January 2010. The Defense Intelligence Agency's Defense Warning Office prepared it under the Advanced Aerospace Weapon System Applications Program. It gives an overview of pulsed high-power microwave sources and the technologies needed to build them, including insulation, cathode materials, high-voltage switching, pulse generators and antennas. The paper concludes that progress requires better cathodes, switching and insulation, and that compact ultrawideband antennas will remain difficult to build.
From the source: Release of 2026-09-18 Incident: 1/28/10, Las Vegas, Nevada. Released with redactions. This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed. This DIRD surveys pulsed high-power microwave (HPM) source technology and argues that such systems remain of military interest because they can disrupt or damage electronic systems with short, intense electromagnetic pulses. The report reviews the main source types and the supporting technologies they depend on, including high-voltage insulation, switching, cathode materials, antennas, and pulse-power generation. It emphasizes the difficulty of building systems that are compact, efficient, and practical to field, since short pulse durations, antenna size, heating, detectability, and beam or signal quality all impose hard engineering limits. Its overall conclusion is that the technology has significant potential military value, but that further progress depends on advances in cathodes, predictive modeling, high-speed high-voltage switching, and low-loss insulation, while compact ultrawideband systems will remain difficult because of basic physical constraints on antenna design.
UNCLASSIFIED/ /POI\ OPPICIAL l:191!! er~LY Adhesion to itself allows casting in several stages without fear of voids or mechanically weakened areas. A final desirable characteristic-one that is of obvious importance-is a very high dielectric strength. With attention to detail and diligence in the casting procedures, dielectric strengths of more then 4 kV/mil on 0.125-inch thickness have been achieved. All these advantages have allowed operation of high-voltage pulse systems at increased power levels and at half the volume of those previously insulated with mineral oil. Urethanes and Silicones These materials are used for casting solid high -voltage equipment, as well as for coating components to reduce the effects of shrinkage or shock. Typically these materials are very hard to use with vacuum casting techniques and, thus, have a much lower dielectric strength than do the best epoxies, especially in larger volumes. Another drawback is that many urethanes and silicones require either moisture or volatile ingredients in the curing process, both of which cause problems with high-voltage systems. Nonetheless, a wide variety of these materials are used in the fabrication of high-voltage pulse systems for applications that require their characteristics. LIQUIDS Liquid insulation has been the primary type of insulation for high-voltage systems since the beginning of the field . Over the years, mineral oils, vegetable oils, hydrocarbons, and even tars and saps have been used as insulation. Dielectric liquids have long served as electrical insulation in power transformers, capacitors, cables, and switching equipment. Several once commonly used fluids are no longer available because of their toxicity and environmental impact. As a result, liquids for insulation that do not have these problems have now been developed for certain applications, including mineral oils, silicon oils, fluoropolymers, and high-molecular-weight paraffin oils. Most of the dielectric fluids made are tailored to the power industry, which accounts for about 99 percent of the demand for these liquids. As a result, many such liquids contain additives that, while necessary for the power industry, are detrimental to high-voltage applications. These include low-vapor-pressure additives for controlling viscosity and antioxidants for improved aging. In addition, most insulating liquids also contain moisture and dissolved gases, which are only weakly bound to the liquid molecules and are easily freed when high electric field stresses are present. Scientists have for years worked to extend the usefulness of transformer oils, fuorinert, and castor oil. They have also developed corona-processing equipment for improving the high-voltage characteristics of insulating oils. This has allowed state-of-the art insulation design using insulating oils and oil-impregnated systems. The corona processing involves flowing the liquid insulation media through a high-field -stress region while under vacuum to remove dissolved gases and low-vapor-pressure constituents from the oil. The liquid is then filtered to remove particles larger than 5 microns. This process improves the corona initiation voltage limit for the liquid and greatly extends the life of components insulated with the media. It has also allowed a significant reduction in the size and, thus, energy density of pulsed transformer systems. GASEOUS Insulating gases are used in many high-voltage applications where weight is a primary issue. Typically the use of gases as an insulating media requires pressurization and, UNCLASSIFIED/ /FOR 0FFI€1Ak Uili ,u1k¥ 4
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Official release, from the pursue collection. The PDF is mirrored here; the original link is above. 37 pages are in the text index: search them above, or from the library's search.